Marine sponges possess complex metabolic systems that support their growth, physiology, and ecological interactions. However, the primary metabolic capacity of the sponge hosts remains incompletely characterized at the molecular level. In this study, we performed de novo transcriptome sequencing of a pooled sample of three individuals of Xestospongia sp. collected in Vietnam, using a high-throughput Illumina sequencing system, to characterize the host-derived metabolic pathways. A total of 43,278 unigenes were assembled, of which 69.15% were functionally annotated using multiple public databases. Functional annotation revealed a broad repertoire of genes associated with core metabolic pathways, including carbohydrate, lipid, and sterol metabolisms, as well as cofactor-related processes. Specifically, complete pathways involved in folate biosynthesis, terpenoid backbone biosynthesis, ubiquinone (Coenzyme Q) metabolism, and steroid biosynthesis were identified, reflecting the independent metabolic framework of the sponge host. Several highly expressed genes related to these pathways, including COQ7, ERG6, NUDX1, QDPR, and PCBD, were detected, and their expression patterns were confirmed by quantitative RT-PCR. Furthermore, protein-based phylogenetic analyses indicated that these genes are closely related to homologous proteins from other sponge species, supporting their host origin. This study provides the first comprehensive transcriptomic resource for Xestospongia sp. from Vietnam, and offers baseline molecular insights into the primary metabolic capacity of the sponge host. These data establish a foundation for future investigations of sponge physiology and host–microbe metabolic partitioning.

Fisheries management in the Mediterranean Sea faces persistent challenges due to the prevalence of data-poor and data-limited stocks, small-scale multi-species fisheries, and limited long-term monitoring programs. Effective assessment methodologies are critical to ensuring sustainable exploitation, yet traditional data-rich stock assessment models remain infeasible for many Mediterranean fisheries. This review provides a comprehensive synthesis of current methodologies developed and applied to assess data-poor fisheries in the Mediterranean context. We examine catch-only approaches, length-based methods, empirical indicators, and multi-indicator frameworks increasingly adopted by the General Fisheries Commission for the Mediterranean (GFCM) and the EU’s Data Collection Framework (DCF). Special attention is given to case studies from the western, central, and eastern Mediterranean that demonstrate the opportunities and limitations of these approaches. We further explore emerging tools, including integrated modeling frameworks, simulation-based harvest control rules, and participatory approaches involving fishers’ local knowledge, to highlight innovations suited to mixed, small-scale Mediterranean fisheries. The review concludes by identifying key gaps in data collection, assessment capacity, and institutional coordination, and proposes a roadmap for improving data-poor fisheries management under Mediterranean-specific ecological, socio-economic, and governance constraints. By consolidating methodological advances and practical lessons, this review aims to provide a reference framework for researchers, managers, and policymakers seeking to design robust, adaptive strategies for sustainable fisheries management in data-limited Mediterranean contexts.

Over the past few decades, the population of cod in the Eastern Baltic has faced numerous challenges due to environmental changes, overfishing, and predation, as well as the effects of infection by third-stage larvae of the Anisakidae parasite in the liver. The aim of this study was to estimate the prevalence and infection level of Anisakidae nematodes in the Eastern Baltic cod stock over a five-year period and analyze the effect of infection on cod health condition. A total of 1946 samples of the Eastern Baltic cod (Gadus morhua) were collected and tested for the presence of Anisakidae nematode larvae. All nematodes found in livers were identified as Anisakidae with an overall prevalence of 30.9%, a mean infection density of 0.8 (median 0.4) nematodes per gram of liver tissue, and a range of 0.01–29.2 nematodes per gram. The prevalence of infection tended to increase with the age of the fish. In multivariate analysis, increasing infection intensity decreased the odds of cod having good Fulton’s and Clark’s condition scores and a hepatosomatic index (HSI) above the population average. While our study shows a clear Anisakidae effect on Fulton’s and Clark’s condition scores and the HSI, these indicators could also be influenced by other environmental, physiological, and pathological factors.

Monitoring fish skin health is essential in aquaculture, where scale loss serves as a critical indicator of fish health and welfare. However, automatic detection of scale loss regions remains challenging due to factors such as uneven underwater illumination, water turbidity, and complex background conditions. To address this issue, we constructed a scale loss dataset comprising approximately 2750 images captured under both clear above-water and complex underwater conditions, featuring over 7200 annotated targets. Various image enhancement techniques were evaluated, and the Clarity method was selected for preprocessing underwater samples to enhance feature representation. Based on the YOLOv8m architecture, we replaced the original FPN + PAN structure with a weighted bidirectional feature pyramid network to improve multi-scale feature fusion. A convolutional block attention module was incorporated into the output layers to highlight scale loss features in both channel and spatial dimensions. Additionally, a two-stage transfer learning strategy was employed, involving pretraining the model on above water data and subsequently fine-tuning it on a limited set of underwater samples to mitigate the effects of domain shift. Experimental results demonstrate that the proposed method achieves a mAP50 of 96.81%, a 5.98 percentage point improvement over the baseline YOLOv8m, with Precision and Recall increased by 10.14% and 8.70%, respectively. This approach reduces false positives and false negatives, showing excellent detection accuracy and robustness in complex underwater environments, offering a practical and effective approach for early fish disease monitoring in aquaculture.

Essential oils (EOs) are increasingly studied as natural anesthetics for fish, offering potential alternatives to synthetic agents. This systematic review aimed to summarize the effects of EOs on Oreochromis niloticus, focusing on their efficacy in inducing sedation and anesthesia, recovery times, and associated physiological responses. A comprehensive search was conducted in the Scopus, Web of Science, and Wiley Online Library databases for studies published up to 10 December 2024. Studies evaluating EOs or their main components in O. niloticus with quantitative data on anesthesia or sedation were included. From 355 records initially identified, studies meeting the inclusion criteria were analyzed qualitatively. EOs rich in compounds such as linalool, carvacrol, and pulegone effectively induced anesthesia in less than 3 min, with recovery times under 10 min, aligning with operational standards for fish anesthesia. However, some EOs caused physiological changes that may be related to stress responses. Variability in experimental protocols and incomplete reporting of chemical composition limited the comparability between studies. EOs demonstrate promising anesthetic potential for O. niloticus, representing safe and environmentally sustainable alternatives. Further standardized and controlled studies are required to confirm their safety and optimize application in aquaculture.

This study was conducted to evaluate the effects of chia seed oil (CSO; Salvia hispanica L.) on the growth performance, haematological-biochemical parameters, immune-related gene expression, and disease resistance to Aeromonas hydrophila in common carp (Cyprinus carpio). The fish were fed diets containing 0%, 0.5%, 1%, and 2% CSO for 60 days. The results showed a significant improvement in final weight, specific growth rate (SGR), and feed conversion ratio (FCR) in fish fed diets containing 1% and 2% CSO compared to the control group. Haematocrit (Hct) and haemoglobin (Hb) levels increased in the CSO groups, while serum triglyceride and cholesterol levels decreased significantly, particularly in the 1% CSO group. The observed decrease in liver enzyme activities (AST, ALT) suggested a hepatoprotective effect of CSO. In the stress test with A. hydrophila, the highest survival rate (80%) was recorded in the 2% CSO group. Furthermore, gene expression analyses performed on spleen tissue revealed an increase in the expression of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-8 in the groups fed with CSO, particularly at the 1% level. These findings indicate that adding 1–2% CSO to carp feed promotes growth, improves lipid metabolism, strengthens immune status, and increases resistance to bacterial infection. Consequently, the use of CSO as a sustainable and functional additive to fish oil in fish feed is suggested.

Atlantic salmon (Salmo salar) populations in the Arctic River Teno (Tana) and other North Atlantic rivers have declined at the same time as pink salmon (Oncorhynchus gorbuscha) have begun to spawn extensively in these rivers in odd-numbered years. In the River Teno, especially, the number of one-sea-year Atlantic salmon ascendants has decreased. In this short review, we assess, based on current information, how the abundance of pink salmon may weaken the survival of Atlantic salmon. Our hypothesis is based on recent evidence from Atlantic salmon in the Baltic Sea showing that the high marine lipid content in the diet of Atlantic salmon post-smolts impairs their growth and survival and is manifested in low numbers of ascendants and in poor thiamine (vitamin B1) status in both juvenile and spawning Baltic salmon. The high energy density of lipids increases the need for thiamine in the metabolism, and the high content of highly unsaturated fatty acids (n–3 HUFAs), like docosahexaenoic acid (DHA, 22:6n–3), in marine fish lipids increases the rate of lipid peroxidation, which consumes thiamine as it acts as an antioxidant against lipid peroxidation. The review presents information that could be used in planning possible future research on the topic.

Rhadinorhynchus is a parasitic genus within the order Echinorhynchida (family Rhadinorhynchidae), comprising over 50 species found in marine ecosystems. The life cycle of Rhadinorhynchus species generally includes marine fish as definitive hosts and zooplankton as intermediate hosts. During a routine marine parasitological survey carried out in temperate waters off the NE Atlantic, we recorded adults (from fish) and cystacanths (from mesozooplankton) of an acanthocephalan morphologically corresponding to the genus Rhadinorhynchus. Species identification as R. lintoni was confirmed based on morphological features. Additionally, new genetic data were added for this species based on several molecular markers, including 18S-ITS1-5.8S-ITS2-28S region of the rRNA gene and cytochrome c oxidase subunit 1 gene. Molecular data also provide evidence of a key trophic transmission involving the primary intermediate host—the euphausiid Nyctiphanes couchii—and higher-level consumers (definitive hosts), including the pelagic fish Sardina pilchardus, Scomber scombrus, and Trachurus trachurus. Genetic matching of different life cycle stages of R. lintoni across these host–parasite assemblages underscores the complexity of transmission dynamics within this ecoregion. These findings are discussed in relation to the growing interest of integrating genetic profiles of host–parasite assemblages to understand the life-cycle of marine parasites, especially for those having seafood security and safety concerns.

Against the backdrop of the continuous expansion of the global aquaculture industry and the growing demand for high-quality feed protein, the development of sustainable alternative protein sources to fishmeal is crucial. Cottonseed protein, particularly cottonseed protein concentrate, has emerged as a highly promising plant-based alternative raw material due to its high protein content and cost advantages. This review systematically evaluates the application effects, challenges, and mechanisms of action of cottonseed protein in fish feed. Core analysis indicates that the primary limiting factor of cottonseed protein is the antinutritional factor free gossypol. High-level replacement (typically >30%) of fishmeal can inhibit fish growth, reduce protein deposition, and impair intestinal health. These adverse effects are closely associated with the downregulation of the hepatic mTOR signaling pathway—a central regulator of protein synthesis and cell growth—shifting the organism’s energy allocation from growth to stress adaptation. Furthermore, the unique fatty acid profile of cottonseed protein may exacerbate energy metabolism imbalance. To overcome gossypol toxicity, physical, chemical, and biological detoxification technologies have been widely applied. Among these, biological methods (such as Bacillus subtilis fermentation and CotA laccase-catalyzed degradation) are particularly outstanding, not only efficiently removing gossypol (removal rate > 90%) but also degrading macromolecular proteins into more digestible and absorbable small peptides and amino acids, significantly enhancing the nutritional value of cottonseed protein. Although the application prospects for cottonseed protein are broad, gaps remain in current research, particularly concerning the deeper metabolic pathways, nutrient utilization efficiency, and long-term impacts on metabolic homeostasis of detoxified cottonseed protein in fish. Future research needs to employ molecular nutrition and multi-omics technologies to elucidate its metabolic mechanisms and optimize detoxification processes and precision feeding strategies. Glandless cottonseed varieties, which fundamentally address the gossypol issue, are considered the most transformative development direction. Through continuous technological innovation, cottonseed protein is expected to become a core feed protein ingredient promoting the sustainable development of the global aquaculture industry.

This study examined the effects of dietary aniseed, thyme, and basil essential oils (EOs) on growth, health, and tissue integrity of common carp (Cyprinus carpio) reared in a recirculating aquaculture system (RAS). Juvenile carp (102 ± 2.8 g) were fed for 12 weeks four isonitrogenous diets: a control and three diets supplemented with 0.2% aniseed (V1), thyme (V2), or basil (V3) oils. Growth performance was not significantly affected (p > 0.05). Flesh biochemical composition improved, with higher protein in V1 (17.85 ± 0.22%) and lower fat in V3 (1.78 ± 0.21%) compared to the control. Hematological parameters and antioxidant enzymes (SOD, CAT, GPx) indicated enhanced immune and oxidative status, while MDA (malondialdehyde) levels decreased. SOD activity increased in treated groups, reaching 4.329 U mg−1 protein in muscle and 4.908 U mg−1 protein in liver in V2, compared to 2.775–3.677 U mg−1 protein (muscle) and 3.508–4.349 U mg−1 protein (liver) in controls. CAT activity was highest in the same group 57.045 U mg−1 protein versus 31.403 U mg−1 protein in controls. Microbiological assessment revealed reduced total aerobic bacteria and Enterobacteriaceae counts in EO-fed fish. Histological analysis showed healthier hepatic and intestinal structures, reduced vacuolation, intact epithelium, and abundant goblet cells in EO-treated groups.